Incoming Federal Reserve Chair Kevin Warsh's talk about "regime change" at the central bank has generated speculation about everything from interest rates to major personnel changes to fundamental alterations in the way it operates and communicates.

But what that eventually might look like is subtler though perhaps more consequential – a rethink of how the Fed manages the financial plumbing in the U.S. economy and the mammoth balance sheet it has built through some 18 years of crisis fighting.